Research On Path Selection Policy For CMT With Transfer Layer Multihoming

With the improvement of Internet, end-to-end communication protocol based on transport layer singlehoming such as TCP and UDP are challenged in aspect of transmission performance, ability of fault tolerance and security. The emergence of end-to-end communication protocol with transport layer multihoming such as SCTP-based CMT (Concurrent Multipath Transfer) greatly improved the end-to-end throughput and network resources utilization.CMT use the same method to establish the association as the SCTP. Data was only sent to Primary Path, at the beginning. But after a short time, data was sent to all paths. Currently, tow ploblems as follows were found in the path selection policy for CMT:(1) The time that the association was established and the whole transport performance of the association both have great relationship with the lossrate of the destination which the sender selected to start the association.The lower the lossrate of the selected destination was the less the time which the association was established and the higher the transport performance was.(2) CMT use the paths which the path’s Cwnd allowed to transmit data without difference not always advanced the transpor performance.The default method is send one packet to all the paths when path’s Cwnd was allowed.These problems were deeply analysed in this thesis, and the CMT-PDS program was proposed. This program mainly active the following two functions:(1) At the beginning of starting the association, the sender select the Primary Path which has the lowest lossrate.(2) The sender of the association selects the path with lowest lossrate as the primary path dynamically during the process of sending data. When the primary path’s Cwnd allowed, send tow packets, when the other path’s Cwnd allowed send only one packet. The program’s goal is to make better path to transmit more data than other path. And the paper simulates the two policies by using the NS2simulation software. Compare the two policies from the aspects of throghput, delay of the packes, the ability of the receiver to process TSN and the capacity at the receiver’s buffer. The results show that the CMT-PDS policy can greatly improve the proformance of data transmission effectively.Finally, the summary of this subject was given in this thesis and a suggestion to the research work of future was outlooked in this thesis too.